The Padres announced they will send left-hander Max Fried, shortstop Jace Peterson, third baseman Dustin Peterson and outfielder Mallex Smith to Atlanta in exchange for Upton and right-hander Aaron Northcraft.

Upton, 27, hit .270 for Atlanta last season, with 29 home runs and 102 RBIs. He will make $14.5 million in 2015 and is set for free agency in 2016.

The trade of Upton had been expected since the Braves signed outfielder Nick Markakis to a four-year, $44 million deal. Atlanta earlier had dealt outfielder Jason Heyward to the St. Louis Cardinals.

The Padres, under new general manager A.J. Preller, have now acquired their entire starting outfield this week: Upton, Matt Kemp and Wil Myers.

On Wednesday, the Padres pulled off a three-team trade to bring Myers from the Tampa Bay Rays.

On Thursday night, the Padres finalized a five-player trade to acquire Kemp from the Los Angeles Dodgers and also obtained All-Star catcher Derek Norris from the Oakland Athletics.

The Padres now are reportedly close to trading catcher Ryan Hanigan, acquired in the deal with Tampa Bay, to Boston for Middlebrooks, who is being replaced by Pablo Sandoval.

Middlebrooks, once considered Boston's future third baseman, has regressed over the last two years. After hitting .288 with 15 homers and 54 RBIs as a rookie in 2012, he hit just .227 in 2013 and .191 in 63 games last season as he split time between Boston and Triple-A Pawtucket.